TinyMCE editor not using CSS style of website?

Hi, can anybody tell me how I align the TinyMCE editor to actually use the CSS styling of my website so that what styles I choose in the editor actually show in the editor how they are seen inside the front of my site - because at the moment it couldnt look
more different !! ?

In the admin folder, there's a file named tinyMCE.ascx. If you open it up, you'll see a bunch of settings. You can add a setting named "content_css" and specify the CSS file in your theme folder for the value. So it will look something
like: